PCA2129T/Q900/2,51 NXP Semiconductors, PCA2129T/Q900/2,51 Datasheet - Page 5

• Manufacturer Part Number: PCA2129T/Q900/2,51
• Description: Real Time Clock
• Manufacturer: NXP Semiconductors
• Series: PCA2129r

Specifications of PCA2129T/Q900/2,51

• Rohs: yes
• Function: Clock, Calendar, Alarm, Watchdog, Timestamp
• Rtc Bus Interface: I2C, SPI
• Date Format: Binary
• Time Format: Binary
• Supply Voltage - Max: 4.2 V
• Supply Voltage - Min: 1.8 V
• Maximum Operating Temperature: + 80 C
• Minimum Operating Temperature: - 30 C
• Mounting Style: SMD/SMT
• Package / Case: SOP-16
• Battery Backup Switching: Yes

NXP Semiconductors
8. Functional description
PCA2129T
Product data sheet
8.1 Register overview
The PCA2129T is a Real Time Clock (RTC) and calendar with an on-chip Temperature
Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartz crystal integrated
into the same package (see
Address and data are transferred by a selectable 400 kHz Fast-mode I
SPI-bus with separate data input and output (see
SPI-bus is 6.5 Mbit/s.
The PCA2129T has a backup battery input pin and backup battery switch-over circuit
which monitors the main power supply. The backup battery switch-over circuit
automatically switches to the backup battery when a power failure condition is detected
(see
supply is interrupted.
A battery low detection circuit monitors the status of the battery (see
the battery voltage drops below a certain threshold value, a flag is set to indicate that the
battery must be replaced soon. This ensures the integrity of the data during periods of
battery backup.
The PCA2129T contains an auto-incrementing address register: the built-in address
register will increment automatically after each read or write of a data byte up to the
register 1Bh. After register 1Bh, the auto-incrementing will wrap around to address 00h
(see
Fig 3.
•
•
•
The first three registers (memory address 00h, 01h, and 02h) are used as control
registers (see
The memory addresses 03h through to 09h are used as counters for the clock
function (seconds up to years). The date is automatically adjusted for months with
fewer than 31 days, including corrections for leap years. The clock can operate in
12-hour mode with an AM/PM indication or in 24-hour mode (see
The registers at addresses 0Ah through 0Eh define the alarm function. It can be
selected that an interrupt is generated when an alarm event occurs (see
Section
Figure
Handling address registers
3).
8.5.1). Accurate timekeeping is maintained even when the main power
All information provided in this document is subject to legal disclaimers.
Section
Rev. 3 — 24 January 2013
Accurate RTC with integrated quartz crystal for automotive
8.2).
Section
address register
1Ah
1Bh
00h
01h
02h
03h
19h
...
8.3.2).
auto-increment
Section
wrap around
001aaj398
9). The maximum speed of the
PCA2129T
Section
Section
2
© NXP B.V. 2013. All rights reserved.
C-bus or a 3 line
8.5.3). When
Section
8.8).
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8.9).